JPS5923409Y2 - solid electrolytic capacitor - Google Patents

Description

[Detailed Description of the Invention] The present invention mainly relates to an improvement of a solid electrolytic capacitor packaged with a glass case.

In general, this type of solid electrolytic capacitor is made of a capacitor element A made by press-molding metal powder having a valve action such as tantalum, niobium, aluminum, etc. into a cylindrical shape and sintering it, as shown in FIG. 1. A functional metal wire is planted as an anode lead B, the protruding end of this anode lead B is welded to the end of the first external lead member C, and the capacitor element A is placed in a cylindrical glass case D. ,
From one opening, the second external lead member E fixed to the other opening of the glass case D is connected to the electrode lead layer F formed on the circumferential surface of the capacitor element A via an oxide layer and a semiconductor layer. In this state, the first external lead member C is fixed to one opening of the glass case D by heat sealing.

By the way, the oxide layer as the dielectric layer of this capacitor tends to deteriorate during the heat treatment process when forming a semiconductor layer such as manganese dioxide on it, and properties such as leakage current and dielectric loss tend to be impaired. For example, when the heat treatment temperature exceeds 200°C, the oxide layer begins to deteriorate and the temperature rises to 500°C.
℃, the leakage current level in particular becomes worse by two orders of magnitude or more.

Therefore, normally, after such a heat treatment process, the oxide layer is repaired by immersing the capacitor niremen (A) in a chemical conversion solution again and carrying out a reconversion treatment.

However, the first external lead member C is placed in the glass case D.
When heat sealing is applied to one opening of the
Since the capacitor element oxide layer is heated to about ~800°C, the oxidation layer of the capacitor element is significantly deteriorated through the anode lead B from the first external lead member C. There is a disadvantage that the quality of the capacitor is significantly impaired because it is not possible to carry out re-formation treatment as after the semiconductor layer forming process.

In view of these points, this project proposes a solid electrolytic capacitor that can alleviate the thermal influence on the capacitor element when fixing an external lead member to a cylindrical case made of a heat-resistant insulating material, and can significantly improve the quality of the capacitor. Examples will be described below.

In FIG. 2, reference numeral 1 denotes a capacitor element made of a metal member having a valve action, and the illustrated example is constructed by press-molding metal powder having a valve action into a cylindrical shape and sintering it.

Reference numeral 2 denotes an anode lead made of a metal wire having a valve action and led out from the capacitor element 1. In the illustrated example, it is planted in the center of the capacitor element 1 prior to pressure forming, but it is welded to its circumferential surface. It is also possible to derive it by

Reference numeral 3 denotes an electrode lead layer formed on the circumferential surface of the capacitor element 10 via an oxide layer and a semiconductor layer, and is constructed by, for example, polymerizing a silver paste layer on a graphite layer. It can also be configured.

4 is a solder layer formed on the electrode lead layer 3, and may be omitted.

Reference numeral 5 denotes a lead member made of a metal member that can be soldered, and the inner end of the lead member 5 is welded to the end face of the anode node 2, for example.

6 is a cylindrical case made of a heat-resistant insulating material such as glass or ceramic, and each opening 6 a
, 6b are formed with solderable metal layers 7 and 8 by an appropriate method such as electroless plating or vapor deposition.

A metal cap 9 is attached to one opening 6a of the case 6 so as to close the opening 6a, and a solder layer 10, for example, is formed on the inner surface of the cap.

Reference numeral 11 denotes a lead member made of a metal member that can be soldered, and is welded, for example, to the center portion of the outer surface of the cap 9.

A solder member 12 is housed in one opening 6a of the case 6, and by melting the solder layer 4 of the capacitor element 1 and the solder layer 10 of the cap 9 are integrally connected.

A metal cap 13 is attached to the other opening 6b of the case 6 so as to close the opening 6b, and a solder layer 14, for example, is formed on the inner surface of the cap.

A hole 15 is formed in the center of it.
A lead member 5 is led out.

Note that the caps 9 and 13 are soldered to the metal layers 7 and 8 of the case 6 with solder layers 10 and 14.

A solder member 16 is soldered to seal the hole in the cap 13.

Next, a method for manufacturing this capacitor will be explained with reference to FIG.

First, as shown in FIG. 5A, the cap 9 is placed in the recessed part of the upper surface of the jig H made of a heat-resistant member so that the lead member 11 is inserted into the hole K.

Then, the case 6 is installed in the cap 9 so that the metal tube 7 is brought into contact with the solder layer 10.

Next, as shown in the figure, the other opening 6b of the case 6
Then, place the solder piece 12' on the cap 9.

Then, capacitor element 1 is placed on this solder piece 12'.
are placed so that the solder layer 4 is in contact with the solder layer 4.

In this state, the other end of the lead member 5 welded to the anode lead 2 protrudes outward from the case 6.

Next, as shown in FIG. 3C, the cap 9 is attached to the other opening 6b of the case 6 with the lead member 5 passing through the hole 15, and the solder layer 14 is brought into contact with the metal layer 8.

In this state, the assembly is inserted into a heating furnace controlled at about 200°C.

Then, the caps 9 and 13 are melted and the metal layers 7 and 14 of the case 6 are melted.
8 are soldered to each other.

At the same time, the solder layer 4 and the solder piece 12' are also melted and integrated with each other.

Next, as shown in FIG. 2D, the assembly is taken out of the heating furnace, and the hole 15 in the cap 13 is hermetically sealed with a solder member 16 to obtain the solid electrolytic capacitor shown in FIG.

In this way, the external lead member consisting of the lead members 5, 11 and the caps 9, 13 is connected to the opening 6a in the case 6.
, 6b are fixed by soldering to the metal layers 7 and 8 of the metal layers 7 and 8, so that the heating temperature when fixing both can be made significantly lower than the conventional heat sealing temperature.

For example, although it varies depending on the composition of the solder material,
The temperature can be reduced to around 0℃.

Therefore, deterioration of the oxide layer in the capacitor element 1 can be suppressed, and the characteristics as a capacitor can be improved.

Further, since the openings 6 a and 6 b at both ends of the case 6 and the cap 9.13, the hole 15 of the cap 13 and the lead member 5 are hermetically sealed with the solder members 10 and 14, 16, the capacitor characteristics are maintained. can be maintained stably for a long period of time, completely unaffected by the atmosphere under use.

Next, specific examples will be described.

First, metal layers made of nickel are formed by electroless plating on both end faces of a case made of lead glass with an outer diameter of 2.6 φ mm, a wall thickness of 0.5 t mm, and a length of 5 mm.

Then, a cap having a lead-tin solder layer formed on the inner surface is attached to one opening of the case, and a solder piece and a capacitor element are sequentially housed in the case.

Then, a cap having a lead-tin solder layer formed on the inner surface is attached to the other opening of the case, with the lead member passing through the hole.

Then, after being placed in a heating furnace controlled at 230° C. for 5 minutes, the hole in the cap is sealed with a solder member.

When we measured the characteristics of this capacitor in parallel with those using conventional methods, we found that the leakage current for this product was on average Q,
2 nA, whereas the conventional product had 10 to 100 nA.
It was A.

Also, with regard to dielectric loss, the present product had little variation, whereas the conventional product had a large variation.

This significant difference in characteristics is thought to be due to the lower heating temperature when the external lead member is fixed to the case.

FIG. 4 shows another embodiment of the present invention, in which, for example, an S-shaped spring member 17 is welded to the inner surface of the cap 13 which is soldered and fixed to the other opening 6b of the case 6. The tip of an anode lead 2 led out from the condenser element 1 is elastically contacted at the free end portion of the anode lead.

According to this embodiment, the node member 5 is fixed to the center of the outer surface of the cap 13 by welding or the like.
By soldering the caps 9, 13 to the openings 6a, 6b of the case 6 with the solder layer 10.14, the openings 6a, 6b can be hermetically sealed, so that workability can be further improved.

Moreover, when external stress acts on the case 6, the spring material 1
7 and does not act on the capacitor element 1, it is possible to prevent characteristic deterioration due to damage to the oxide layer and semiconductor layer.

FIG. 5 shows a further different embodiment of the present invention, which is basically the same as the embodiment shown in FIG.
, 13 are completely omitted.

According to this embodiment, the same effects as the above embodiment can be obtained, and since the lead member is omitted, it can be directly connected to a component mounting body such as a printed circuit board, and the assembly can be made smaller. It is possible to measure the

Note that the present invention is not limited to the above embodiments in any way,
For example, the metal layer of the case can be formed by plating, vapor deposition, or the like, or by attaching a solder material with a relatively high melting point while applying ultrasonic waves.

In addition to using the solder layer formed on the cap, the case and the cap can be soldered using a ring-shaped solder member, and in addition to being soldered on the end face of the case, it is also possible to solder the solder on the inner surface of the case. It can also be done in parts.

Furthermore, the cap can also be configured simply in the form of a plate.

As described above, according to the present invention, the thermal influence on the capacitor element when the external lead member is airtightly fixed to the case made of the heat-resistant insulating member can be alleviated, and the quality of the capacitor can be significantly improved.

[Brief explanation of the drawing]

Fig. 1 is a front sectional view of a conventional example, Fig. 2 is a front sectional view showing an embodiment of the present invention, Fig. 3 is a front sectional view for explaining the manufacturing method, and Figs. 4 and 5 are a front sectional view of the invention. FIG. 6 is a front sectional view showing other different embodiments. In the figure, 1 is a capacitor element, 2 is an anode lead, 3
is an electrode extraction layer, 6 is a case, 6a, 6b are openings, 7
, 8 is a metal layer, 9.13 is a cap, and 12 is a solder member.

Claims (1)

[Scope of utility model registration request] A condenser element made of a metal member with a valve action, with an electrode lead layer formed on its circumferential surface through an oxide layer and a semiconductor layer, and a metal wire with a valve action led out as an anode lead, and a condenser element housed therein. A cylindrical case made of a heat-resistant insulating material with a metal layer formed thereon that can be soldered to the opening; A solid electrolytic capacitor comprising a fixed metal cap, the anode lead of the capacitor element being electrically connected to one cap, and the electrode lead layer being soldered to the other cap.